Bismuth triphenyl jet fuel compositions and process of using same



BISMUTH TRIPHENYL JET FUEL COMPDSITIONS AND PROCESS OF USING SAIWE Donald R. Stevens, Wilkinsburg, and Ronald L. Sweet, Baldwin Borough, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa, a corporation of Delaware No Drawing. Application December 21, 1953, Serial No. 399,606

4 Claims. 01. 60 35.4

This invention relates to an improved liquid hydrocarbon fuel and a process of burning such fuel whereby the tendency of the fuel to form carbonaceous deposits and/r smoke is substantially reduced or inhibited.

The preparation of commercial fuel oils, that is, fuel oils having A. P. I. gravities in the range of about to about 40, and particularly from about 14 to about 36, which will burn with little or no accompanying smoke is a serious problem in the industry. Fuel oils are in general unrefined hydrocarbon distillates .and residuals whose initial boiling points are above about 350 F. Their tendency to smoke increases with their molecular weight and olefin and aromatic content. In commercial practice an abundance of high-boiling hydrocarbons for use as fuel oils is on hand from thermal and catalytic cracking operations. These hydrocarbons are generally high in olefin and aromatic content and therefore are susceptible to burning with a smoky flame. Since a low smoke number is generally included in fuel oil specifications it has often been necessary in the past to blend these high-boiling hydrocarbons with petroleum material, which could be more advantageously utilized in some other manner, say as a preferred charging stock to the cracking stills for gasoline manufacture.

Difiiculty has also been experienced in the past in the burning of jet fuels in gas turbines in that appreciable amounts of carbon are deposited in the combustor. The carbon formed in the combustion zone is believed to result from either incomplete combustion or else from the pyrolysis (thermal cracking) of the fuel between the time it leaves the spray nozzle until it reaches the flame zone. Carbon deposition is serious because its collection on the combustor affects the heat dissipation therefrom which: may give rise to extensive warpage. The carbon deposits, as they build up, also adversely affect the mixing of the air and the fuel, either by partial or complete clogging of the air ports or by disturbing the normal fuel spray pattern and turbulence in the combustor.

We have found that liquid hydrocarbon fuel compositions having improved burning characteristics can be prepared by incorporating in such fuel a relatively small amount of bismuth triphenyl. While the amount of bismuth triphenyl which must be incorporated in the liquid hydrocarbon fuel to obtain the desired results should be at least about 0.005 percent by .weight, based upon the fuel, for best results we prefer to use about 0.01 to about 0.1 percent by weight of bismuth triphenyl. Amounts of bismuth triphenyl higher than about 0.1 percent by weight can be used and the improvement noted above will still be obtained, but ordinarily are not desirable because of the additional costs involved and also because we have often observed in our studies on combustion improvers that when higher percentages of additives are used the response per unit of addition decreases with the additional amount employed. In any event, the amountof bismuth triphenyl used is sufficient to inhibit the formation of undesirable products of combustion.

2,806,348 "Patented Sept. 17, 1957 2 The hydrocarbon fuels which are used in our process and which are benefited by the addition thereto of hismuth triphenyl are those which, during burning thereof,

- smoke and/or deposit carbon in or near the combustion area. Examples of hydrocarbon fuels which fall within the scope of our invention include fuel oils prepared directly from unrefined hydrocarbon distillates and residuals which are burned for the generation of heat in a furnace or fire box, said fuel oils having A. P. I. gravities in the range from about 10 to about 40, and particularly from about 14 to about 36; jet fuels such as are used in gas turbine engines; and diesel fuels burned for the generation of power in a diesel engine, such engine merely illustrative of the invention and that otherfuel oils can also be effectively used in the practice thereof. The specifications of the fuel. oil employed in the test were as follows:

API gravity, 60 F 35.7 Specific gravity, 60/60 F 0.8463 Lbs./gal., 60 F 7.047 Vis.cs., F 2.63 SUSZI 100 F 34.8 77 F- 3.46 Flash, F Distillation:

Initial F -363 10% 434 50% 502 90% 566 End point 611 Recovery 98.9 Heat value:

(B. t. u./gal.) 135,380 (B. t. u./lb.) 19,637 Carbon residue on 10% bottoms 0.03 Neutralization number 0.03 Sulfur, percent 0.25 Aniline point, C 60.5 Refractive index, 20 C 1.4752 Pour point, F -5 Smoke tests were run on the fuel oil alone and on the fuel oil plus controlled amounts of bismuth triphenyl by a method in which stack gases from a fuel oil burner are drawn through a filter paper disc for two minutes. These tests were run in a domestic, vertical, rotary, cut-type burner manufactured by the Automatic Burner Corporation and designated Model H. The burner has a capacity of one to two gallons per hour, and its motor operates at 3500 revolutions per minute. In the tests, the burner was operated at feed rates in the neighborhood of eight to ten pounds per hour.

. Each of the samples of fuel oil was burned and a. stream of flue gas resulting from the combustion was induced to pass through a small filter paper disc. The disc was held in la properly designated frame and maintained in the flue at a point approximately 21% inches from the furnace outlet in accordance with U. S. Department of Commerce Bulletin CS-10446. The discs are made of No. 4 Whatman filter paper and have an effec-- tive diameter of inch. Flue gas was drawn through. the disc for a period of two minutes while maintaining generally having a compression ratio ofabout 12 to about 2 A inches of mercury diiferential pressure across the disc. I V

To determine the smoking characteristics of the fuel, tests were made on the filter paper while using a photocell meter with a 50-lwatt bulb. installed therein. The readings are obtained by inserting the disc between the light source and, the photocell insuch a way that part of the light energy is absorbed and/ or reflected away from the photocell.: Changes of light intensity on the photocellare indicatedon a laboratory grade long scale microammeter.

.In using this meter, a piece of clean filter paper is first inserted in the disc, holder and the voltage adjusted to give anfinitial microammeter reading of 160. This. paper is then used in the smoke sampler, and followingits remo al, is aga n nser d: in h ligh e s ty m ter. Th vol a e is dj s d, t es rne valu aine with h cl an. is nd/ a new e d ng of i r mp r i a edjh e r a i ,m e oamperes be o the ini i l value of 160 is applied to a calibration curve and a value of smoke density measured. By this method, variations in the filter paper and the light transmitting properties of the light source are compensated for. The scale employed to determine the amount of smoke" uses the number toindicate a totally black disc and a very smoky fuel. (one of zero efiiciency) whileat the other end of the sc ale a perfectly clean disc would have-a smoke number of'O. I V

The'results of runs made with the samples of the fuel oil identified above, alone and with controlled amounts of bismuth triphenyl, in accordance with the test hereinahove described is. set forth below in Table I.

Table 1 Percent Decrease in Smoke Number Decrease in Smoke Number Smoke Disc Concentration of Additive, Spot Percent by Weight Number \rocove V willbe" seen from the data in'Table I that "amounts as low as 0.05 percent by weight of bismuth triphenyl in fuel oil will reduce the smoke number 32.5 percent. Bismuth triphenyl' in amounts of 0.5 percent by weight will decrease the smoke number of such fuel 34.1 percent, although, as will be apparent from the table, the greatest benefit per unit amount is with the lower weight.

In general a reduction in stack temperature was noted when the combustion improver was added to the fuel oil in the'above-tests'. This is believed to occur because less soot 'is deposited onthe heat exchanger coils labove the fire box, with the result'that more heat is dissipated to the water in the coils and less is allowed to go up the stack. Thus, the benefits obtained from our invention are apparent, for coils heavily coated with soot are inefficientin absorbing heat from the flue. gases and more B. t. us will be lost to the exit gases.

" Combustion tests were also conducted on jet fuels having incorporated therein controlled amounts of bismuth triphenyl to determine the reduction of carbon deposits effected thereby. The small scale aviation gas burner test stand used for rating the carbon deposition tendencies of gas turbine (jet) fuels was essentially an apparatus which. provides for the feeding of a mixture of a metered supply of air (held at constant temperature and pressure) and a metered supply of filtered fuel to a tubular burner sectionwhere combustion takes place (after ignition by a spark plug The burner section, the outside cylinder of which is rnlade of Pyrex glass (about 3 /2 inchesin diameter) to permit visual observation, is provided with a cone-shaped combustor containing an orifice at the small end through which the fuel is supplied to produce a spray; f'lhe incomingair is admixed with the fuel spray throughports in the combustor wall, and the combustion takes place within 'the walls of the stainless steel combustor tube. The air supply holes in the combustor are evenly distributed but are of varied size. Those near the primary burning zone are smaller (thus limiting the air supply at this point) than those near the secondary zone.

This design was purposely chosen so 'as to encourage a' The following conditions are malntained throughout the test: p a

Inlet air temperature:

Orifice inlet F. Burner inlet F.

Air pressure '50 in, mercury absolute.

Fuel flow 1x875 lbs/hr.

Fuel-air ratio 0.0115.

Duration of run 30 minutes.

The JP-4 referee base fuel employed in the tests had the following composition and specification:

Gravity, API (D287) 45.9 Specific gravity, 60/60 F 0,7976 Viscosity/ 100 F centistokes 0939 Copper strip corrosion (D-50T) (3 hours/- 212 F.) 0. Water (Karl Fischer), weight percent 0.0046

Distillation. (D86) (barometric pressure 745.1):

Initial B. P., F End point, F 522 V 90% v 457 Recovery 98.5

. Residue 1.0 Sulfur (lamp), percent 0.292 Carbon, percent 0 87.21 Hydrogen, percent 1 13.21

I-Iydrogen/carbon 0-.1515

Gum:

Preformed, mg./100 ml .i. 16.6

,Accelerated,,mg./1'0.0 ml 12.6 Freezing point, F -65 Doctor test; Sweet Heat of combustion cal 18,606 Bromine number (D1158) 11.4 Aromatics, (D875), vol. percent 24.6 Aniline point (D611'A) F 10855 Vapor pressure (D323) lb 2.1

The results of the above tests are set forth below in Table II. a

Table II V Combustor Deposit Percent by Weight Bismuth Triphenyl V Wt. (g.) Reduction Percent in Wt. (g.) Reduction The combustor is cleaned and'weighedTbefor'e' In addition, some carbon generally accurnu- L m m It will be seen from Table II that bismuth triphenyl in amounts as low as 0.005 percent by weight in jet fuels will reduce combustion deposits by 13.1 percent. Additional amounts of bismuth triphenyl will result in a greater reduction in carbon deposits. Maximum reduction in carbon deposits, 52.5 percent, is obtained, however, by incorporating in the jet fuel 0.05 percent by weight of bismuth triphenyl. Bismuth triphenyl in amounts greater than 0.05 percent by weight will also result in a reduction in carbon deposits, although the reductions become less with increasing amounts of additive. In fact, 0.2 percent by weight of bismuth triphenyl gives substantially the same results as 0.005 percent. For best results, as the data in Table II show, we prefer to employ bismuth triphenyl in amounts between about 0.01 and 0.1 percent by weight and preferably between about 0.03 and about 0.08 percent by weight.

The examples disclosed herein are merely illustrative and our invention is not to be considered limited thereto. Thus, our invention comprehends not only the liquid hydrocarbon fuels defined above, but also such fuels having incorporated therein additives normally added thereto for a specific purpose, such as corrosion inhibitors, antioxidants, stabilizers for the prevention of sludge formation, etc.

While our invention has been described and defined as improving the combustion properties of liquid hydrocarbon fuels, it is also within the scope of our invention to employ bismuth triphenyl to improve the burning properties of other materials so that the burning will approximate that of a more highly refined product. Thus, bismuth triphenyl can be employed as such or as an ingredient in compositions for coating coal or as a constituent in chemical propellants, black powder, flares and pyrotechnic products, matches and other organic material where combustion is accompanied by smoke and/ or undesirable amounts of carbon deposition.

Obviously, many modifications and variations of the invention, as hereinabove set forth, can be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. The method of operating a jet engine which comprises supplying to the combustion zone of said jet engine a liquid hydrocarbon jet fuel containing about 0.01 to about 0.08 percent by Weight of bismuth triphenyl; burning said fuel in the combustion zone of said engine; and exhausting resulting gases from said engine so as to impart thrust thereto, whereby combustion deposits are reduced.

2. The method of operating a jet engine which comprises supplying to the combustion zone of said jet engine a liquid hydrocarbon jet fuel containing about 0.03 to about 0.08 percent by weight of bismuth triphenyl; burning said fuel in the combustion zone of said engine; and exhausting resulting gases from said engine so as to impart thrust thereto, whereby combustion deposits are reduced.

3. A fuel for use in a jet engine which will result in decreased combustion deposits when burned in the combustion zone thereof, comprising a liquid hydrocarbon jet fuel having the following specification:

Copper strip corrosion (D130-50T):

(3 hours/212 F.).. 0

6 Water (Karl Fischer), wt. percent 0.0046 Distillation (D86) barometric pressure 745.1):

Heat of combustion cal 18,606

Bromine number (D1158) 11.4 Aromatics (D875), vol. percent 24.6 Aniline point (D611A) F 108.5 Vapor pressure (D323) lb; 2.1

having incorporated therein about 0.01 to about 0.08 percent by weight of bismuth triphenyl.

4. A fuel for use in a jet engine which will result in decreased combustion deposits when burned in the combustion zone thereof, comprising a liquid hydrocarbon jet fuel having the following specification:

Gravity, A. P. I. (D287) 45.9 Specific gravity, 60/60 F 0.7976 Viscosity/ F centistokes 0.939 Copper strip corrosion (D-50T):

(3 hours/212 F.) 0 Water (Karl Fischer), Wt. percent 0.0046 Distillation (D86) (barometric pressure 745.1):

Initial B. P., F

End point, F 522 10% 236 50% 343 90% 457 Recovery 98.5

Residue 1.0

Sulfur (lamp), percent 0.292

Carbon, percent 87.21

Hydrogen, percent 13.21

Hydrogen/carbon 0.1515 Gum:

Preformed, mg./100 ml 6.6

Accelerated, mg./ 100 ml 12.6 Freezing point, F 65 Doctor test Sweet Heat of combustion cal 18,606

Bromine number (D1158) 11.4 Aromatics (D875), vol. percent 24.6 Aniline point (D611A) F 108.5 Vapor pressure (D323) lb 2.1

Midgley Mar. 2, 1926 Midgley July 20, 1926 

1. THE METHOD OF OPERATING A JET ENGINE WHICH COMPRISES OF SUPPLYING TO THE COMBUSTION ZONE OF SAID JET ENGINE A LIQUID HYDROCARBON JET FUEL CONTAINING ABOUT 0.01 TO ABOUT 0.08 PERCENT BY WEIGHT OF BISMUTH TRIPHENYL; BURNING SAID FUEL ON THE COMBUSTION ZONE OF SAID ENGINE; AND EXHAUSTING RESULTING GASES FROM SAID ENGINE SO AS TO IMPART THRUST THERETO, WHEREBY COMBUSTION DEPOSITS ARE REDUCED. 